Do Probiotic Products Live Up to Their Promises?

A daily dose of good bacteria can boost your health, but not all foods containing probiotics are created equal. Find out which are the best to add to your diet.

You’ve probably heard the term “probiotics” thrown around in your doctor’s office or grocery store, especially regarding some staple foods in your kitchen, includingyogurt, kefir, and kimchi. You might’ve also caught wind that probiotics are living microorganisms (including common bacterial strains like Lactobacillus and Bifidobacterium as well as yeast), but not the scary kind that make you sick. It’s the opposite: Probiotics support proper body function by stimulating the immune system, promoting digestion, inhibiting growth of potentially harmful bacteria that lead toinfections, and producing key nutrients, such as B vitamins and folate. That’s not all: Probiotics have also shown to alleviate diarrhea and constipation, decrease the duration of colds, aid weight loss, and lower cholesterol and blood pressure levels.

While researchers have proven over the last two decades through 6000+ studies (60 percent of which were published in the last five years) that these invisible-to-the-naked-eye organisms are good for your health, it’s still unclear which probiotics to consume to reap the most rewards. Though fermented foods are nothing new—they’ve been around for more than 7,000 years, starting with fermented fruits, milk (aka kefir), meats, pickled vegetables, bread, beer, and wine —which are the best is still a mystery. What’s more confusing is that shelves are being stocked with more probiotics-infused products—including frozen burritos, cold-brewed coffee, even protein powder—plus supplements than ever before.

Related: Should You Be Eating More Fermented Foods?

“With food sources versus supplements, there’s more potential to buy a product that doesn’t contain probiotics—or if it does, those probiotics may not be viable,” says Lynne V. McFarland, Ph.D., affiliate associate professor in the department of medicinal chemistry at the University of Washington and co-author of The Power of Probiotics: Improving Your Health with Beneficial Microbes. “There is no quality control for the efficacy of probiotic strains in most grocery store foods.”

This is exactly why experts say it’s important to choose a brand that’s transparent about any probiotic strains present. “It takes a great deal of product development to ensure the survival of probiotics in processed foods, but it has been done successfully,” says Wendy J. Dahl, Ph.D., associate professor of food science and human nutrition at University of Florida. “Some processed foods have quite ingenious ways of probiotic administration—for example, probiotics in the straw of a beverage and probiotics in yogurt-flavored balls in breakfast cereals.” When foods are pasteurized, as with yogurt or baked, the probiotic would have been killed due to heat, but may have been added back in after heating. This is possibly the case with foods such as the aforementioned burrito.